1. Field of the Invention
The present invention relates generally to producing optical elements for use in optical systems.
2. Description of the Related Art
In many optical systems it is common to assume that the light passing through the system is limited to paraxial rays, specifically, rays that are near the optical axis and that are sustained within small angles. With this assumption, corrective optics having only spherical surfaces can correct aberrations that are present in images generated by the optical systems. While aspheric optics can be produced, to do so is costly and time consuming.
An example of the above problem is the human eye. It is conventionally assumed that ocular imperfections are limited to lower order imperfections, including the imperfections commonly called “astigmatism” and “defocus”, that can be corrected by lenses having spherical surfaces. However, in reality optical systems including the human eye rarely are limited to what is conventionally assumed for purposes of providing corrective optics that have only spherical surfaces. In the case of the human eye, for instance, higher order imperfections can exist, including but not limited to those imperfections known as “coma” and “trefoil”. These imperfections unfortunately cannot be corrected by conventional glasses or contact lenses, leaving patients with less than optimum vision even after the best available corrective lenses have been prescribed.
Moreover, as recognized by the present invention, it is often difficult to simultaneously minimize all aberrations. Indeed, corrections to an optical system to minimize one type of aberration may result in the increase in one of the other aberrations. As but one example, decreasing coma can result in increasing spherical aberrations.
Furthermore, it is often necessary to correct aberrations in an optical system that are introduced during manufacturing. This process can be iterative and time consuming, requiring, as it does, assembly, alignment, and performance evaluation to identify aberrations, followed by disassembly, polishing or grinding to correct the aberrations, and then reassembling and retest. Several iterations might be needed before a suitable system is developed.
Having recognized the above-noted problems, the invention provides the below-disclosed solutions to one or more of them.